In particular, the invention relates to a determining device comprising:                a light source capable of emitting a rectilinearly polarised light beam in a predefined direction, the light beam being intended to be reflected by the measurement point of the target sample,        a means for calculating the polarisation information for the measurement point from the beam reflected by the target sample.        
U.S. Pat. No. 7,289,211 describes an example of such a determining device.
Such a device for determining polarisation information provides information on the micro or nanostructure of target samples, and on their texture at the surface or slightly beneath the surface. This polarisation information can be, for example, the phase shift or the degree of polarisation of the beam returned by the target sample. This information is primarily used in the medical field for diagnosis, and in the field of microelectronics for characterizing single-layer or multi-layer thin films or for analyzing complex surfaces.
Generally, the polarisation information is obtained by reflecting a polarised light beam on a target sample. Polarisation information for the target sample can be determined by analyzing the polarisation of the reflected beam.
This technique requires the use of a light beam with direct line of sight to and unencumbered space around the target area. It is not possible to measure polarisation information from an object situated in an area difficult to access, inside a cavity, or in an obscuring environment.
One goal of the invention is to overcome this disadvantage and provide a device for determining a piece of polarisation information which allows, among other things, analyzing target samples not accessible by a light beam with direct line of sight.